The present invention is directed to methods and devices for nebulizing fluids. In a specific application of the present invention, the device is used to nebulize fluids for delivery to the lungs. Although the present invention is particularly useful for nebulizing fluids for inhalation, it is understood that the present invention may be used for nebulizing fluids in other fields and for other purposes.
In a first aspect of the present invention, a nebulizing device is provided which has at least two nebulizing elements. In a preferred embodiment, the nebulizing element has a vibrating element with a plurality of apertures. The vibrating element is preferably a relatively stiff element, such as a rigid dome-shaped element, but may be any other suitable structure. The vibrating elements are vibrated to expel fluid through the apertures.
The device may be operated to provide independent delivery of two different fluids. In a specific application of the present invention for nebulizing liquids for inhalation, the first fluid may contain an immune modulator or a mucolytic, such as alpha domase, and the second fluid could contain an antibiotic, such as an aminoglycocide like tobramicin, or quinolone, pentamidine, or an antifungal such as amphotericin B. Another application for the device is for the first fluid to contain a short acting beta agonist and the second fluid to contain a corticosteroid. The beta agonist provides symptomatic relief and the corticosteroid treats the underlying immune reaction. The beta agonist may be any suitable beta agonist such as albuterol. These drugs complement one another in the treatment of asthma. Other combinations of drugs may be delivered with the device which relate to the same ailment or to different ailments.
The first and second fluids may also be delivered in the same breath. In one aspect, the first fluid may be delivered earlier than the second fluid. For example, the first fluid could contain a bronchodilator which opens the lungs for delivery of the second fluid. Alternatively, the second fluid could be a bronchorestrictor delivered after the first fluid to help retain the first fluid in the lungs. Of course, any combinations of liquids may be delivered as the first and second fluids and the examples given are merely illustrative.
Although the device may be operated to deliver two or more fluids, the device may be used to deliver a single fluid. When delivering only one fluid, the combination of nebulizers provides enhanced flow. For example, the nebulizing elements may together be used to deliver 40-300 microliters, more preferably 100-250 microliters, in one breath. Stated another way, the nebulizing elements are used to deliver at least 100 microliters and more preferably at least 200 microliters of fluid in one breath by the user. Stated still another way, the device delivers the preferred amounts in no more than four seconds of operating time. The first and second nebulizers also provide the ability to provide relatively large increases and decreases in fluid flow rate by simply activating or de-activating one or more of the nebulizers. Of course, the flow rate of each of the nebulizers may be adjusted by changing the power or frequency of operation.
In another aspect of the present invention, the nebulizer may also instruct or permit the user to inhale a set number of doses over a period of time. For example, the device may permit and/or instruct the user to inhale six doses of the first fluid, such as a beta agonist, per day and only two doses of the second fluid, such as a corticosteroid. The control system may also permit a set number of doses of one of the fluids in relation to the amount of the other fluid delivered. In this manner, the relative amounts of the two fluids can be regulated.
The present invention is also directed to a flow director which may be used with the nebulizing devices of the present invention. As mentioned above, the present invention is directed to nebulizing fluids for inhalation but may be used for any other purpose. The nebulizing device has a vibrating element with a plurality of apertures therein. The vibrating element has a front side and a back side with the plurality of apertures extending between the front and back sides. A flow director is positioned adjacent to the back side of the vibrating element and defines a dispensing chamber therebetween. The flow director provides various advantages as described below. One advantage of the flow director is that the flow director can help to remove and reduce bubbles produced in the dispensing chamber.
In a preferred embodiment, an outlet chamber receives bubbles that may form in the dispensing chamber. The outlet chamber may have an active feature to accelerate bubble collapse, such as a source of heat, cold or electrical energy, or a passive feature, such as a protrusion, surface features or a coating. The inlet is preferably positioned below the outlet so that bubbles naturally migrate upward toward the outlet. In a preferred embodiment, the flow director is positioned 0.003-0.015 inch, and more preferably 0.003-0.030 inch from the back side of the vibrating element to form a relatively small volume in the dispensing chamber. The dispensing chamber preferably holds 2-40 micoliters and more preferably 2-30 microliters. The relatively small size of the dispensing chamber and proximity of the flow director together and independently may tend to inhibit bubble formation and prevent an accumulation of bubbles.